Polycarbonate resin composition

ABSTRACT

The invention relates to a polycarbonate resin composition having good durability even in high-moisture atmospheres, and to a flame-retardant polycarbonate resin composition in which the flame retardants adheres little to molds while the resin composition is molded. The polycarbonate resin composition comprises (A) a polycarbonate resin and (B) an inorganic filler, and contains (C) an arylphosphine and optionally (D) a flame retardant.

This application is a Division of Ser. No. 09/868,037 Oct. 23, 2001 nowU.S. Pat. No. 6,476,178 which is a 371 of PCT/JP00/06996 filed Oct. 6,2000.

TECHNICAL FIELD

The present invention relates to a polycarbonate resin composition. Moreprecisely, the invention relates to a polycarbonate resin compositionhaving good durability even in high-humidity atmosphere, and to aflame-retardant polycarbonate resin composition in which the flameretardant adheres little to molds.

BACKGROUND ART

As having the advantages of impact resistance, heat resistance and goodelectric properties, polycarbonate resins have many applications invarious fields of, for example, OA (office automation) appliances,information and communication appliances, other electric and electronicappliances for industrial use and household use, automobile parts andbuilding materials. Polycarbonate resins are self-extinguishable.However, some fields of typically OA appliances, information andcommunication appliances, and other electric and electronic appliancesfor industrial use and household use require higher flame retardancy,for which are used various flame retardants to improve their flameretardancy.

For improving the flame retardancy of polycarbonate resins,halogen-containing flame retardants such as bisphenol A halides andhalogenated polycarbonate oligomers have been used along with a flameretardation promoter such as antimony oxide, as their flame-retardingability is good. However, with the recent tendency toward safety livingand environmental protection from discarded and incinerated wastes, themarket requires flame retardation with non-halogen flame retardants. Asnon-halogen flame retardants, phosphorus-containing organic flameretardants, especially organic phosphate compounds may be added topolycarbonate resin compositions, for which various methods have beenproposed. Such flame retardants, organic phosphate compounds serve alsoas a plasticizer, and polycarbonate resin compositions containing themexhibit excellent flame retardancy.

It is known to stabilize polycarbonate resins with organic phosphoruscompounds added thereto, for example, as in Japanese Patent PublicationNo. 22088/1972 and Japanese Patent Laid-Open No. 90254/1985. However, inorder to make polycarbonate resins resistant to flames by adding theretoa phosphate compound, a relatively large amount of the compound must beadded to the resins. Polycarbonate resins require relatively highmolding temperatures, and their melt viscosity is high. Therefore, formolding them into thin-walled and large-sized moldings, the moldingtemperature will have to be more and more higher. For these reasons,phosphate compounds often cause some problems when added to suchpolycarbonate resins, though their flame-retarding ability is good. Forexample, phosphate compounds often adhere to molds used for moldingresins containing them, and, when the moldings containing them are leftin high-temperature and high-humidity atmospheres, the compounds lowerthe impact strength of the moldings and yellow the moldings.

In Japanese Patent Laid-Open No. 283760/1990, proposed is a method ofadding a hydroxyl group-having phosphorus compound such as phosphorousacid or phosphoric acid to a polycarbonate resin composition containingan inorganic filler, for stabilizing the filler in the composition. Inthis case, the phosphorus compound added to the resin composition iseffective for stabilizing the inorganic filler in the composition.However, this is problematic in that, when the moldings of the resincomposition are used in high-humidity atmospheres, their durability islowered as the molecular weight of the polycarbonate resin therein islowered, and, in addition, it is often difficult to recycle themoldings.

In Japanese Patent Laid-Open Nos. 228764/1995 and 239565/1996, proposedis a polycarbonate resin composition comprising a polycarbonate resinand a styrenic resin and containing a phosphate compound and talc.

When polycarbonate resins containing an inorganic filler such as talcare molded at high temperatures or when their moldings are recycled, themolecular weight of the resins is lowered to cause some problems in thatthe physical properties of the resin moldings are worsened and themoldings are much yellowed.

The present invention is to provide a polycarbonate resin compositionhaving good durability even in high-humidity atmospheres and to providea flame-retardant polycarbonate resin composition in which the flameretardant adheres little to molds.

DISCLOSURE OF THE INVENTION

We, the present inventors have assiduously studied in order to solve theproblems in the prior art, and, as a result, have found that, when asuitable amount of an arylphosphine is added to a resin compositioncomprising a polycarbonate resin and an inorganic filler, then theabove-mentioned object can be attained. On the basis of this finding, wehave completed the present invention.

Specifically, the invention is summarized as follows:

[1] A polycarbonate resin composition comprising (A) from 50 to 99.9% byweight of a polycarbonate resin and (B) from 0.1 to 50% by weight of aninorganic filler, and containing (C) from 0.01 to 1 part by weight,relative to 100 parts by weight of the total of (A) and (B), of anarylphosphine of a general formula [1]:

P−(X)₃   [1]

wherein X represents a hydrocarbon group, and at least one X is anoptionally-substituted aryl group having from 6 to 18 carbon atoms.

[2] The polycarbonate resin composition of above [1], wherein theinorganic filler (B) is talc or mica.

[3] The polycarbonate resin composition of above [1] or [2], wherein theinorganic filler (B) is talc having a mean particle size of from 0.2 to20 μm.

[4] The polycarbonate resin composition of any of above [1] to [3],wherein the arylphosphine (C) is triphenylphosphine.

[5] The polycarbonate resin composition of any of above [1] to [4],which further contains (D) from 0.1 to 20 parts by weight, relative to100 parts by weight of the total of the polycarbonate resin (A) and theinorganic filler (B), of a flame retardant.

[6] The polycarbonate resin composition of above [5], wherein the flameretardant (D) is one or more selected from the group of phosphates, redphosphorus and silicone compounds.

[7] The polycarbonate resin composition of above [5] or [6], whichfurther contains (E) from 1 to 40 parts by weight, relative to 100 partsby weight of the total of the polycarbonate resin (A) and the inorganicfiller (B), of a styrenic resin.

[8] The polycarbonate resin composition of above [7], wherein thestyrenic resin (E) is a rubber-modified styrenic resin.

[9] The polycarbonate resin composition of any of above [5] to [8],which further contains (F) from 0.01 to 5 parts by weight, relative to100 parts by weight of the total of the polycarbonate resin (A) and theinorganic filler (B), of a polyfluoro-olefin resin.

[10] The polycarbonate resin composition of above [9], wherein thepolyfluoro-olefin resin (F) is a polytetrafluoroethylene having theability to form fibrils and having a mean molecular weight of at least500,000.

[11] Housings or parts of electric and electronic appliances, made bymolding the polycarbonate resin composition of any of above [1] to [10].

BEST MODES OF CARRYING OUT THE INVENTION

The invention is described in detail hereinunder.

(A) Polycarbonate Resin:

The polycarbonate resin for the component (A) that constitutes thepolycarbonate resin composition of the invention is not specificallydefined in point of its chemical structure and production method, andvarious polycarbonate resins are usable herein. For example, preferredare aromatic polycarbonate resins that are produced through reaction ofdiphenols and carbonate precursors.

For these, various diphenols are usable. For example, preferred are2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)methane,1,1-bis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 4,4′-dihydroxydiphenyl,bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl) ether,bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) sulfone,bis(4-hydroxyphenyl) sulfoxide, bis(4-hydroxyphenyl) ketone,hydroquinone, resorcinol, and catechol. Of the diphenols, more preferredare bis(hydroxyphenyl)alkanes, in particular,2,2-bis(4-hydroxyphenyl)propane. The diphenols may be used either singlyor as combined.

The carbonate precursors for use in the invention include, for example,carbonyl halides, carbonyl esters, and haloformates, more concretely,phosgene, diphenol dihaloformates, diphenyl carbonate, dimethylcarbonate, and diethyl carbonate.

Regarding its chemical structure, the molecular chain of thepolycarbonate resin may have a linear, cyclic or branched structure. Forthe branching agent for the polycarbonate resin having a branchedstructure, for example, preferred are 1,1,1-tris(4-hydroxyphenyl)ethane,α,α′,α″-tris(4-hyroxyphenyl)-1,3,5-triisopropylbenzene, phloroglucine,trimellitic acid, and isatin-bis(o-cresol). The polycarbonate resin maybe a polyester-polycarbonate resin produced from ester precursors, forexample, difunctional carboxylic acids such as terephthalic acid ortheir ester-forming derivatives. Various types of differentpolycarbonate resins may be mixed to give mixed polycarbonate resins foruse in the invention.

The viscosity-average molecular weight of the polycarbonate resin mayfall generally between 10,000 and 50,000, but preferably between 13,000and 35,000, more preferably between 15,000 and 20,000. Theviscosity-average molecular weight (Mv) is obtained as follows: Theviscosity of the polycarbonate resin in a methylene chloride solution at20° C. is measured with an Ubbelohde's viscometer, and the limitingviscosity [η] thereof is derived from it. The viscosity-averagemolecular weight (Mv) of the resin is calculated according to theequation, [η]=1.23×10⁻⁵ Mv^(0.83). For controlling the molecular weightof the polycarbonate resin, for example, employable are phenol,p-t-butylphenol, p-t-octylphenol, and p-cumylphenol.

The polycarbonate resin may also be a polycarbonate-polyorganosiloxanecopolymer. The copolymer can be produced, for example, by dissolving apolycarbonate oligomer and a polyorganosiloxane having a terminalreactive group in a solvent such as methylene chloride, adding theretoan aqueous solution of a diphenol in sodium hydroxide, and reacting themin a mode of interfacial polycondensation in the presence of a catalystsuch as triethylamine. The polyorganosiloxane structure in the copolymeris preferably any of a polydimethylsiloxane structure, apolydiethylenesiloxane structure, a polymethylphenylsiloxane structureor a polydiphenylsiloxane structure.

Also preferably, the degree of polymerization of the polycarbonatemoiety of the polycarbonate-polyorganosiloxane copolymer falls between 3and 100 or so, and that of the polyorganosiloxane moiety thereof fallsbetween 2 and 500 or so. Also preferably, the polyorganosiloxane moietycontent of the polycarbonate-polyorganosiloxane copolymer falls between0.5 and 30% by weight, more preferably between 1 and 20% by weight. Alsopreferably, the viscosity-average molecular weight of thepolycarbonate-polyorganosiloxane copolymer falls between 5,000 and100,000, more preferably between 10,000 and 30,000.

(B) Inorganic Filler:

The inorganic filler for the component (B) includes, for example, talc,mica, kaolin, diatomaceous earth, calcium carbonate, calcium sulfate,barium sulfate, glass fibers, carbon fibers, and potassium titanate. Ofthose, preferred are tabular talc and mica. Talc is a hydrous silicateof magnesium, and any commercially-available products of it areemployable herein. Talc for use herein may have a mean particle size offrom 0.1 to 50 μm, but preferably from 0.2 to 20 μm.

(C) Arylphosphines:

Arylphosphines for the component (C) are represented by theabove-mentioned formula [1]. In formula [1], X indicates a hydrocarbongroup, and at least one X is an optionally-substituted aryl group havingfrom 6 to 18 carbon atoms.

The arylphosphines of the type include, for example, triphenylphosphine,diphenylbutylphosphine, diphenyloctadecylphosphine,tris(p-tolyl)phosphine, tris(p-nonylphenyl)phosphine,tris(naphthyl)phosphine, diphenyl(hydroxymethyl)phosphine,diphenyl(acetoxymethyl)phosphine,diphenyl(β-ethylcarboxyethyl)phosphine, tris(p-chlorophenyl)phosphine,tris(p-fluorophenyl)phosphine, diphenylbenzylphosphine,diphenyl-β-cyanoethylphoshpine, diphenyl(p-hydroxyphenyl)phosphine,diphenyl-1,4-dihydroxyphenyl-2-phosphine, andphenylnaphthylbenzylphosphine. One or more of these arylphosphines maybe used herein either singly or as combined. Of the arylphosphines,especially preferred is triphenylphosphine.

(D) Flame Retardant:

The flame retardant for the component (D) includes, for example, organicphosphorus compounds, non-halogen phosphorus compounds and siliconecompounds.

The organic phosphorus compounds are preferably phosphate compounds, forexample, those of the following general formula, and their oligomers andpolymers.

wherein R¹, R², R³and R⁴ each independently represent a hydrogen atom,or a substituted or unsubstituted alkyl, cycloalkyl, aryl, alkoxy,aryloxy, arylthio, arylalkoxyalkyl or arylsulfonylaryl group; Xrepresents a substituted or unsubstituted alkylene, phenylene,biphenylene or naphthalene group; p is 0 or 1; q is an integer of 1 orlarger; and r is 0 or an integer of 1 or larger.

Specific examples of the phosphate compounds of the formula aretrimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctylphosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresylphosphate, cresyldiphenyl phosphate, octyldiphenyl phosphate,tri(2-ethylhexyl) phosphate, diisopropylphenyl phosphate, trixylenylphosphate, tris(isopropylphenyl) phosphate, trinaphthyl phosphate,bisphenol A bisphosphate, hydroquinone bisphosphate, resorcinolbisphosphate, resorcinol-diphenyl phosphate, trihydroxybenzenetriphsophate, and cresyldiphenyl phosphate, their substitutedderivatives, and their oligomers and polymers. One or more thesephosphate compounds may be in the resin composition either singly or ascombined.

For the non-halogen phosphorus compound, preferred is red phosphorus.Red phosphorus for use herein may be non-processed, but is preferablystabilized through surface treatment with, for example, any ofthermoplastic resins or inorganic compounds. The thermoplastic resinsinclude, for example, phenolic resins, phenol-formalin resins, urearesins, urea-formalin resins, melamine resins, melamine-formalin resins,alkyd resins, epoxy resins, and unsaturated polyester resins. Theinorganic compounds include, for example, silica, bentonite, zeolite,kaolin, titanium oxide, zinc oxide, magnesium oxide, magnesiumcarbonate, barium sulfate, calcium phosphate, aluminium hydroxide,magnesium hydroxide, zinc hydroxide, and titanium hydroxide.

The silicone compounds are preferably functional group-having siliconecompounds, such as functional group-having (poly)organosiloxanes. Fortheir skeletons, they may be polymers or copolymers having a basicstructure of a formula, R¹ _(a)R² _(b)SiO_((4−a−b)/2) wherein R¹indicates a functional group-containing group; R² indicates ahydrocarbon group having from 1 to 12 carbon atoms; 0<a≦3, 0≦b<3, and0<a+b≦3. The functional group includes, for example, an alkoxy group, anaryloxy group, a polyoxyalkylene group, a hydrogen group, a hydroxylgroup, a carboxyl group, a cyanol group, an amino group, a mercaptogroup, and an epoxy group. One silicone compound may have a plurality offunctional groups. A plurality of silicone compounds each having adifferent functional group may be combined for use herein. In thefunctional group-having silicone compounds, the ratio of the functionalgroup (R¹) to the hydrocarbon group (R²) preferably falls between 0.1and 3 or so, more preferably between 0.3 and 2 or so.

The silicone compounds are liquid or powdery, and preferred for useherein are those well dispersible with the resin component when kneadedin melt with it. Of the liquid silicone compounds, preferred are thosehaving a viscosity at room temperature of from 10 to 500,000 centistokesor so. Even though liquid, the functional group-having siliconecompounds uniformly disperse in the resin composition of the invention,and bleed little while the resin composition is molded and on thesurface of the resin moldings.

(E) styrenic Resin:

For the styrenic resin for the component (E), usable are homopolymers ofmonovinylic aromatic monomers such as styrene and α-methylstyrene;rubber-modified styrenic resins obtained through polymerization of suchmonovinylic aromatic monomers in the presence of a rubber-like polymer;copolymers of monovinylic aromatic monomers and vinyl cyanide monomerssuch as acrylonitrile and methacrylonitrile; copolymers of the monomerswith other vinylic comonomers copolymerizable with them, such asmaleimide and methyl (meth)acrylate; and mixtures of these styrenicresins.

Of the styrenic resins, especially preferred are rubber-modifiedstyrenic resins. The rubber-modified styrenic resins include, forexample, high-impact styrenic resins produced throughgraft-polymerization of rubber-like polymers with styrenic monomers,such as high-impact polystyrenes (HIPS) produced through polymerizationof rubber such as polybutadiene with styrene; ABS resins producedthrough polymerization of polybutadiene with acrylonitrile and styrene;MBS resins produced through polymerization of polybutadiene with methylmethacrylate and styrene.

In the rubber-modified styrenic resins, the amount of the rubber-likepolymer may fall generally between 2 and 50% by weight, but preferablybetween 5 and 30% by weight, more preferably between 5 and 15% byweight. If the rubber-like polymer content is smaller than 2% by weight,the resin composition will have poor impact resistance. If, on the otherhand, it is larger than 50% by weight, the thermal stability of theresin composition will be lowered, and the melt fluidity thereof will bealso lowered. If so, the resin composition will be unfavorably gelled oryellowed. Specific examples of the rubber-like polymer includepolybutadiene, acrylate and/or methacrylate-having rubber-like polymers,styrene-butadiene-styrene (SBS) rubber, styrene-butadiene rubber (SBR),butadiene-acrylic rubber, isoprene rubber, isoprene-styrene rubber,isoprene-acrylic rubber, ethylene-propylene rubber, andethylene-propylene-diene rubber.

Of the rubber-modified styrenic resins, more preferred are thosemodified with polybutadiene. The polybutadiene for them may be any oflow-cis polybutadiene (for example, having from 1 to 30 mol % of1,2-vinyl bonds and from 30 to 42 mol % of 1,4-cis bonds) or high-cispolybutadiene (for example, having at most 20 mol % of 1,2-vinyl bondsand at least 78 mol % of 1,4-cis bonds).

Preferably, the styrenic resin for the component (E) has a melt index(MI), measured at a temperature of 200° C. under a load of 49N accordingto JIS K7210, falls between 1 and 30 g/10 min, more preferably between 2and 20 g/10 min.

(F) Polyfluoro-olefin Resin:

The polyfluoro-olefin resin for the component (F) in the polycarbonateresin composition of the invention may be a polymer or copolymer havinga fluoro-ethylenic structure. Concretely, it includes difluoroethylenepolymers, tetrafluoroethylene polymers,tetrafluoroethylene-hexafluoropropylene copolymers, and copolymers oftetrafluoroethylene with fluorine-free ethylenic monomers. of those,most preferred is polytetrafluoroethylene (PTFE) desirably having a meanmolecular weight of at least 500,000, more desirably from 500,000 to10,000,000.

Of the polytetrafluoroethylene, more preferred is one having the abilityto form fibrils, as its property of preventing the melts of thepolycarbonate resin composition from dropping is better.

The blend ratio of the components (A) and (B) in the polycarbonate resincomposition of the invention is such that the polycarbonate resin (A)accounts for from 50 to 99.9% by weight and the inorganic filler (B)accounts for from 0.1 to 50% by weight. Preferably, the polycarbonateresin (A) accounts for from 80 to 95% by weight, and the inorganicfiller (B) accounts for from 5 to 20% by weight.

If the blend ratio of the polycarbonate resin (A) therein is smallerthan 50% by weight, the resin composition could hardly retain the heatresistance and the mechanical strength intrinsic to the polycarbonateresin. If the blend ratio of the inorganic filler (B) is smaller than0.1% by weight, the toughness and the light diffusibility of the resinmoldings will be poor; but if larger than 50% by weight, the moldabilityof the resin composition will be poor.

The blend ratio of the arylphosphine (C) falls between 0.01 and 1 partby weight, preferably between 0.01 and 0.3 parts by weight, relative to100 parts by weight of the resin composition comprising from 50 to 99.9%by weight of the polycarbonate resin (A) and from 0.1 to 50% by weightof the inorganic filler (B). If the blend ratio of the component (C) issmaller than 0.01 parts by weight, the durability in high-humidityatmospheres of the resin moldings containing the inorganic filler suchas talc will lower; but even if larger than 1 part by weight, thedurability in high-humidity atmospheres of the resin moldings could notbe augmented any more.

The blend ratio of the flame retardant (D) falls between 0.1 and 20parts by weight, relative to 100 parts by weight of the resincomposition comprising from 50 to 99.9% by weight of the polycarbonateresin (A) and from 0.1 to 50% by weight of the inorganic filler (B). Asso mentioned hereinabove, various types of flame retardants are usablefor the component (D). In case where a phosphate is used, its blendratio preferably falls between 5 and 10 parts by weight relative to 100parts by weight of the resin composition of (A) and (B). In case wherered phosphorus is used, its blend ratio preferably falls between 0.5 and2 parts by weight relative to 100 parts by weight of the resincomposition. In case where a silicone compound is used, its blend ratiopreferably falls between 0.5 and 10 parts by weight relative to 100parts by weight of the resin composition. This is because, if the blendratio of the flame retardant is lower than the lowermost limit of therange, the flame retardancy of the resin composition will be poor; butif over the range, the mechanical strength including the impactresistance and the heat resistance of the resin moldings will lower.

One embodiment of the polycarbonate resin composition of the inventioncomprises from 50 to 99.9% by weight of the polycarbonate resin (A) andfrom 0.1 to 50% by weight of the inorganic filler (B), and contains from0.01 to 1 part by weight, relative to 100 parts by weight of the totalof (A) and (B), of the arylphosphine (C) of formula [1] and from 0.1 to20 parts by weight, relative to the same, of the flame retardant (D).The polycarbonate resin composition comprising these components (A),(B), (C) and (D) is a good molding material capable of being molded intomoldings having high mechanical strength and good heat resistance andhaving good flame retardancy. Another advantage of the resin compositionis that, when it is molded in a mode of injection molding, it is freefrom the problem of flame retardant adhesion to molds which is oftenseen when conventional, flame retardant-containing resin compositionsespecially those containing a phosphate-type flame retardant areinjection-molded.

The blend ratio of the styrenic resin (E) in the polycarbonate resincomposition of the invention falls between 1 and 40 parts by weight,preferably between 10 and 20 parts by weight, relative to 100 parts byweight of the resin composition comprising from 50 to 99.9% by weight ofthe polycarbonate resin (A) and from 0.1 to 50% by weight of theinorganic filler (B). Containing the styrenic resin (E), the meltfluidity and the chemical resistance of the resin composition and itsmoldings are improved. If, however, its blend ratio is smaller than 1part by weight, the styrenic resin (E) will be ineffective for improvingthe melt fluidity and the chemical resistance of the resin composition.If, on the other hand, the blend ratio of the styrenic resin (E) islarger than 40 parts by weight, the proportion of the essentialingredient, polycarbonate resin in the resin composition shall berelatively low, and the mechanical strength and the heat resistance ofthe resin moldings will be thereby lowered.

Another embodiment of the polycarbonate resin composition of theinvention comprises from 50 to 99.9% by weight of the polycarbonateresin (A) and from 0.1 to 50% by weight of the inorganic filler (B), andcontains from 0.01 to 1 part by weight, relative to 100 parts by weightof the total of (A) and (B), of the arylphosphine (C) of formula [1],from 0.1 to 20 parts by weight, relative to the same, of the flameretardant (D), and from 1 to 40 parts by weight, relative to the same,of the styrenic resin (E). This is a flame-retardant polycarbonate resincomposition having good melt fluidity.

The blend ratio of the polyfluoro-olefin resin (F) in the polycarbonateresin composition of the invention falls between 0.01 and 5 parts byweight, preferably between 0.1 and 0.5 parts by weight, relative to 100parts by weight of the resin composition comprising from 50 to 99.9% byweight of the polycarbonate resin (A) and from 0.1 to 50% by weight ofthe inorganic filler (B). If its blend ratio is smaller than 0.01 partsby weight, the polyfluoro-olefin resin (F) will be ineffective forfurther improving the flame retardancy of the resin composition; buteven if larger than 5 parts by weight, its effect could not be augmentedany more.

Still another embodiment of the polycarbonate resin composition of theinvention comprises from 50 to 99.9% by weight of the polycarbonateresin (A) and from 0.1 to 50% by weight of the inorganic filler (B), andcontains from 0.01 to 1 part by weight, relative to 100 parts by weightof the total of (A) and (B), of the arylphosphine (C) of formula [1],from 0.1 to 20 parts by weight, relative to the same, of the flameretardant (D), from 1 to 40 parts by weight, relative to the same, ofthe styrenic resin (E), and from 0.01 to 5 parts by weight, relative tothe same, of the polyfluoro-olefin resin (F). This is a flame-retardantpolycarbonate resin composition having the advantage of well-balancedphysical properties.

The polycarbonate resin composition of the invention may furthercontain, in addition to the above-mentioned components, some desiredamount of additives that are generally added to ordinary thermoplasticresins and their compositions. The additives include, for example,antioxidants, antistatic agents, UV absorbents, light stabilizers(weathering agents), plasticizers, microbicides, compatibilizers, andcolorants (dyes, pigments).

A method for producing the flame-retardant polycarbonate resincomposition of the invention is described. The composition may beproduced by mixing and kneading the components (A) to (F) and optionaladditives in a ratio desired for the properties of the moldings of thecomposition. Formulating and mixing the constituent components into theintended resin composition may be effected in any known manner, usingany known mixer or kneader. For example, the constituent components arepre-mixed in an ordinary device, such as a ribbon blender or a drumtumbler, and then further kneaded in a Henschel mixer, a Banbury mixer,a single-screw extruder, a double-screw extruder, a multi-screwextruder, or a cokneader. The temperature at which the components aremixed and kneaded generally falls between 240 and 300° C. Formelt-kneading and molding the resin composition, preferably used is anextrusion molding machine, and more preferred is a vented extrusionmolding machine. Other components than the polycarbonate resin may bepreviously mixed with polycarbonate resin or with any otherthermoplastic resin to prepare a master batch, and it may be added tothe other constituent components.

Having been prepared in the manner noted above, the flame-retardantpolycarbonate resin composition of the invention may be molded intovarious moldings in the melt-molding devices as above, or, after it ispelletized, the resulting pellets may be molded into various moldingsthrough injection molding, injection compression molding, extrusionmolding, blow molding, pressing, or foaming. Especially preferably, thecomposition is pelletized in the melt-kneading manner as above, and theresulting pellets are molded into moldings through injection molding orinjection compression molding. For injection molding of the composition,employable is a gas-assisted injection molding method so as to preventshrinkage cavity around the moldings and to reduce the weight of themoldings. The moldings produced in the method are lightweight and havegood appearance.

The moldings of the polycarbonate resin composition of the invention areusable for various housings and parts of electric and electronicappliances, such as duplicators, facsimiles, televisions, radios, taperecorders, video decks, personal computers, printers, telephones,information terminals, refrigerators, and microwave ovens. Except forsuch electric and electronic appliances, the moldings have still otherapplications, for example, for automobile parts.

The invention is described more concretely with reference to thefollowing Examples and Comparative Examples.

[EXAMPLES 1 TO 4, AND COMPARATIVE EXAMPLES 1 TO 6]

[1] Production of Polycarbonate Resin Compositions:

The components shown in Table 1 were blended in the ratio indicatedtherein (all by weight), fed into a vented double-screw extruder (TEM35from Toshiba Kikai), melted and kneaded therein at 260° C., and thenpelletized. Prior to melting and kneading the components, 0.2 parts byweight of Irganox 1076 (from Ciba Specialty Chemicals) and 0.1 parts byweight of Adekastab C (from Asahi Denka Industry) both serving as anantioxidant were added to all the starting materials in Examples andComparative Examples.

The resulting pellets were dried at 120° C. for 12 hours, and thenmolded into test pieces in a mode of injection molding at 270° C. Themold temperature was 80° C.

The molding materials used herein are mentioned below.

Component (A):

PC-1 in Table 1 is a polycarbonate resin, Toughlon A1900 (from IdemitsuPetrochemical), for which the starting material is bisphenol A. Theresin has a melt index, measured at a temperature of 300° C. under aload of 11.76 N, of 20 g/10 min, and has a viscosity-average molecularweight of 19,000. PC-2 in Table 1 is apolycarbonate-polydimethylsiloxane copolymer resin comprisingpolycarbonate block units (for these, the starting material is bisphenolA), and containing 4% by weight of polydimethylsiloxane block units (30units in total). The copolymer resin has a viscosity-average molecularweight of 20,000.

Component (B):

Talc is TP-A25 (from Fuji Talc), having a mean particle size of 1.2 μm.Glass fibers are chopped fibers of MA409C (from Asahi Fiber Glass),having a fiber diameter of 13 μm and a length of 3 mm.

Component (C):

TPP in Table 1 is an arylphosphine, triphenylphosphine from HokkoChemical.

Component (D):

Flame retardant-1 in Table 1 is a flame retardant, PFR (from Asahi DenkaKogyo). This is resorcinol bis(diphenyl phosphate). Flame retardant-2 isCR741 (from Daihachi Chemical Kogyo). This is bisphenol bis(diphenylphosphate). Flame retardant-3 is KR219 (from Shin-etsu Chemical). Thisis methylphenylsilicone having vinyl and methoxy groups.

Component (E):

HIPS in Table 1 is a rubber-modified styrenic resin, high-impactpolystyrene IT44 (from Idemitsu Petrochemical), having a rubber contentof 7% by weight, and a melt index, measured at a temperature of 200° C.under a load of 49 N, of 8 g/10 min. ABS is an ABS resin,acrylonitrile-butadiene-styrene copolymer DP611 (from Technopolymer),having a melt index, measured at a temperature of 200° C. under a loadof 49 N, of 2 g/10 min.

Component (F):

PTFE in Table 1 is a polyfluoro-olefin resin, polytetrafluoroethyleneCD076 (from Asahi Glass).

[2] Evaluation of Polycarbonate Resin Compositions:

Test pieces of the polycarbonate resin compositions obtained in theabove [1] were tested for their properties, according to the testmethods mentioned below.

(1) Izod Impact Strength:

Measured according to ASTM D-256. The temperature is 23° C., and thethickness of samples is ⅛ inches.

(2) Flexural Modulus:

Measured according to ASTM D-790. The temperature is 23° C., and thethickness of samples is 4 mm.

(3) In-Line Thermal Stability (at 300° C. for 20 Minutes) Based on ΔE:

An injection-molding machine (Toshiba Kikai's 100EN Model) is used. Thecylinder temperature is kept just at 300° C. A resin composition to betested is molded into square plates having an outer size of 80 mm×80 mmand a thickness of 3.2 mm. First, the sample is molded in an ordinarymanner for 10 shots. Then, the sample is metered, fed into the machineand kept therein for 20 minutes. After having been thus kept in themachine, this is molded, and the color of the first to third shotmoldings is measured. The data are averaged, and the average color isreferred to as the color of the sample kept heated at 300° C. for 20minutes in the machine. This is compared with the color of the freshsample not kept heated in the machine, and the color difference isreferred to as ΔE. For measuring the color of the test pieces, used isMachbeth's Color-Eye.

(4) In-Line Thermal Stability Based on ΔMv of PC:

The injection-molding machine (Toshiba Kikai's 100EN Model) is used. Thecylinder temperature is kept just at 300° C. A resin composition to betested is molded into square plates having an outer size of 80 mm×80 mmand a thickness of 3.2 mm. First, the sample is molded in an ordinarymanner for 10 shots. Then, the sample is metered, fed into the machineand kept therein for 20 minutes. After having been thus kept in themachine, this is molded, and the viscosity-average molecular weight (Mv)of the first to third shot resin melts is measured. The data areaveraged. The averaged value is compared with the viscosity-averagemolecular weight of the fresh sample not kept heated at 300° C. for 20minutes in the machine; and the difference between the two is referredto as ΔMv.

(5) Adhesion of Molding Material to Mold:

The injection-molding machine (Toshiba Kikai's 100EN Model) is used, andthis is equipped with a mold for square plates having an outer size of80 mm×80 mm and a thickness of 3.2 mm. The cylinder temperature is keptjust at 300° C. The amount of the resin composition to be fed into themold is so controlled that it gives a molding having a size of 40 mm×80mm. This means that the resin composition to the mold is metered forshort-shot molding. After 120 shots, the mold is macroscopically checkedfor the adhesion of the flame retardant thereto.

(6) Thermal Aging Resistance:

Test pieces are molded, and kept in an oven at 80° C. for 10 days.Having been thus aged under heat, these are tested.

<1>Izod Impact Strength:

The aged test pieces are measured according to ASTMD-256, at 23° C.Their thickness is ⅛ inches.

<2>Color Change:

The color of the aged test pieces is measured with Machbeth's Color-Eye,and compared with that of the non-aged fresh pieces.

(7) Moisture Resistance:

Test pieces are molded, and kept in a thermo-hygrostat at a temperatureof 60° C. and a humidity of 95%, for 1000 hours. Having thus absorbedmoisture, these are tested.

<1>Izod Impact Strength:

The aged test pieces are measured according to ASTMD-256, at 23° C.Their thickness is ⅛ inches.

<2>Color Change:

The color of the aged test pieces is measured with Machbeth's Color-Eye,and compared with that of the non-aged fresh pieces.

(8) Recyclability:

Using the injection-molding machine, Toshiba Kikai's 100EN Model, theresin composition obtained in the above [1] is molded, and the moldingsare ground in a grinder. The thus-ground powder is again molded in thesame manner as previously. The cycle of molding and grinding is repeated5 times, and the moldings obtained in the 6th molding cycle are testedfor the recyclability of the sample.

<1>Izod Impact Strength:

The recycled moldings are measured according to ASTM D-256, at 23° C.Their thickness is ⅛ inches.

<2>Color Change:

The color of the recycled moldings is measured with Machbeth'sColor-Eye, and compared with that of the fresh moldings.

(9) Flame Retardancy:

Using the injection-molding machine, Toshiba Kikai's 100EN Model, theresin composition obtained in the above [1] is molded into bars havingan outer size of 127 mm×12.7 mm and a thickness of 1.5 mm. The bars aretested for their flame retardancy, according to the combustion test ofUL94 V-0.

The test results are given in Tables 1-1 to 1-3.

TABLE 1-1 Example, Comparative Example Example 1 Comp. Ex. 1 Comp. Ex. 2Blend Ratio (A) PC-1 90 90 90 PC-2 — — — (B) Talc 10 10 10 Glass Fibers— — — (C) TPP 0.1 — — Phosphoric Acid — — 0.1 Test Results Izod ImpactStrength (kJ/m²) 15 5 12 Flexural Modulus (MPa) 3400 3500 3400 In-lineThermal Stability 3 20 8 (at 300° C. for 20 minutes), ΔE In-line ThermalStability, ΔMv of PC 3500 8000 6000 Thermal Aging Resistance, IzodImpact Strength 13 2 5 (kJ/m²) Thermal Aging Resistance, Color Change ΔE3 9 6 Moisture Resistance, Izod Impact Strength 10 1 2 (kJ/m²) MoistureResistance, Color Change ΔE 5 12 15 Recyclability, Izod Impact Strength(kJ/m²) 15 3 12 Recyclability, Color Change ΔE 2 5 3 Flame Retardancy(1.5 mm, UL94) V-2 V-2 V-2

TABLE 1-2 Example, Comparative Example Example 2 Comp. Ex. 3 Comp. Ex. 4Blend Ratio (A) PC-1 90 90 90 PC-2 — — — (B) Talc 10 10 10 Glass Fibers— — — (C) TPP 0.2 — — Phosphoric Acid — — 0.2 (D) Flame Retardant-1 1010 10 Flame Retardant-2 — — — Flame Retardant-3 — — — (E) HIPS 20 20 20ABS — — — (F) PTFE 0.3 0.3 0.3 Test Results Izod Impact Strength (kJ/m²)30 20 25 Flexural Modulus (MPa) 3600 3600 3600 In-line Thermal Stability2 5 3 (at 300° C. for 20 minutes), ΔE In-line Thermal Stability, ΔMv ofPC 2000 3500 2500 Adhesion to Mold (at 280° C.) no yes yes Thermal AgingResistance, Izod Impact Strength 25 10 15 (kJ/m²) Thermal AgingResistance, Color Change ΔE 3 8 8 Moisture Resistance, Izod ImpactStrength 25 5 5 (kJ/m²) Moisture Resistance, Color Change ΔE 5 10 15Recyclability, Izod Impact Strength (kJ/m²) 30 10 25 Recyclability,Color Change ΔE 2 4 3 Flame Retardancy (1.5 mm, UL94) V-0 V-1 V-1

TABLE 1-3 Example, Comparative Example Example 3 Comp. Ex. 5 Example 4Comp. Ex. 6 Blend Ratio (A) PC-1 80 80 65 65 PC-2 — — 30 30 (B) Talc — —5 5 Glass Fibers 10 10 — — (C) TPP 0.1 — 0.2 — Phosphoric Acid — 0.1 — —(D) Flame Retardant-1 — — — — Flame Retardant-2 10 10 — — FlameRetardant-3 — — 2 2 (E) HIPS — — — — ABS 20 20 10 10 (F) PTFE 0.3 0.30.3 0.3 Test Results Izod Impact Strength (kJ/m²) 12 12 50 35 FlexuralModulus (MPa) 4100 4100 2900 3000 In-line Thermal Stability 2 2 2 4 (at300° C. for 20 minutes), ΔE In-line Thermal Stability, ΔMv of PC 10001500 1000 3000 Adhesion to Mold (at 280° C.) no yes — — Thermal AgingResistance, Izod Impact Strength 11 8 45 20 (kJ/m²) Thermal AgingResistance, Color Change ΔE 3 6 2 4 Moisture Resistance, Izod ImpactStrength 10 4 40 15 (kJ/m²) Moisture Resistance, Color Change ΔE 4 8 4 6Recyclability, Izod Impact Strength (kJ/m²) 11 11 50 25 Recyclability,Color Change ΔE 2 2 2 4 Flame Retardancy (1.5 mm, UL94) V-0 V-1 V-0 V-2out

In Table 1 above, the data of Example 1 are compared with those ofComparative Example 1. It is understood that the polycarbonate resincontaining talc only is much deteriorated, concretely, the impactstrength of the resin moldings is lowered and the color change thereofis great in the moisture resistance test. This means thattriphenylphosphine added to the composition of polycarbonate resin andtalc is effective for preventing the resin from being deteriorated. Thedata of Example 1 are compared with those of Comparative Example 1. Itis understood that the known composition comprising polycarbonate resin,talc and phosphoric acid (described in Japanese Patent Laid-Open No.283760/1990) is not deteriorated so much, but the impact strength of itsmoldings is lowered and the color change thereof is great in the thermalaging resistance test and the moisture resistance test.

The data of Example 2 are compared with those of Comparative Examples 3and 4. It is understood that adding triphenylphosphine to thecomposition comprising polycarbonate resin and styrenic resin andcontaining a flame retardant resulted in further improving the flameretardancy of the resin composition. In addition, the thermal agingresistance and the moisture resistance of the resin composition areimproved with no adhesion of the flame retardant to molds.

The data of Example 3 are compared with those of Comparative Example 5.It is understood that, when glass fibers are used for the inorganicfiller in place of talc, the same results are obtained. The data ofExample 4 are compared with those of Comparative Example 6. It isunderstood that, when a silicone-type flame retardant is used in placeof the phosphate-type flame retardant, the same results are obtained.

INDUSTRIAL APPLICABILITY

The present invention provides a polycarbonate resin composition havinggood durability even in high-moisture atmospheres, and provides aflame-retardant polycarbonate resin composition having good flameretardancy. While molded, the resin composition adheres little to molds.

What is claimed is:
 1. A polycarbonate resin composition comprising (A)from 50 to 99.9% by weight of a polycarbonate resin and (B) from 0.1 to50% by weight of an inorganic filler selected from the group consistingof talc, mica, kaolin, diatomaceous earth, calcium carbonate, calciumsulfate, barium sulfate, glass fibers, carbon fibers, and potassiumtitanate, and containing (C) from 0.01 to 1 part by weight, relative to100 parts by weight of the total of(A) and (B), of an arylphosphine offormula (1): P−(X)₃  (1) wherein X represents a hydrocarbon group, andat least one X is an optionally-substituted aryl group having from 6 to18 carbon atoms.
 2. The polycarbonate resin composition as claimed inclaim 1, wherein the inorganic filler (B) is talc or mica.
 3. Thepolycarbonate resin composition as claimed in claim 2, wherein theinorganic filler (B) is talc having a mean particle size of from 0.2 to20 μm.
 4. The polycarbonate resin composition as claimed in claim 1,wherein the arylphosphine (C) is triphenylphosphine.
 5. Thepolycarbonate resin composition as claimed in claim 1, which furthercontains (D) from 0.1 to 20 parts by weight, relative to 100 parts byweight of the total of the polycarbonate resin (A) and the inorganicfiller (B), of a flame retardant.
 6. The polycarbonate resin compositionas claimed in claim 5, wherein the flame retardant (D) is one or moreselected from the group consisting of phosphates, red phosphorus, andsilicone compounds.
 7. The polycarbonate resin composition as claimed inclaim 5, which further contains (F) from 0.01 to 5 parts by weight,relative to 100 parts by weight of the total of the polycarbonate resin(A) and the inorganic filler (B), of a polyfluoro-olefin resin.
 8. Thepolycarbonate resin composition as claimed in claim 7, wherein thepolyfluoro-olefin resin (F) is a polytetrafluoroethylene having theability to form fibrils and having a mean molecular weight of at least500,000.
 9. Housings or parts of electric and electronic appliances,made by molding the polycarbonate resin composition of claim 1.